- Scientists from the National Bureau of Plant Genetic Resources have collected several wild species related to wheat, containing valuable stress-resistant traits, from the Kashmir region.
- The wild varieties in this collection assume importance as wheat productivity is expected to decline due to challenges associated with global climate change.
- Several of these wild varieties already show the ability to withstand diseases, drought and salinity, traits that scientists hope to transfer to cultivated wheat through a focused breeding programme.
In the year 2014, when Jammu and Kashmir was facing one of its worst floods, a group of researchers from the National Bureau of Plant Genetic Resources (NBPGR) and Punjab Agricultural University (PAU) were in Ladakh collecting wild plants. This wasn’t a random walk into the wilderness but a targeted search for wild cousins of the wheat plant.
Cut off from the main Kashmir valley due to the floods, the researchers carried on, undaunted. This field excursion and a couple of others, the next year, in 2015, resulted in the collection of 169 different samples of wheat-like plants growing in the wilds of Ladakh. The samples are now preserved safely at the NBPGR headquarters in New Delhi, in refrigerators maintained at minus 20 degrees Celsius.
Wild relatives of plants, especially of food crops, have become attractive to researchers and breeders because of their ability to better withstand the vagaries of nature. Growing in the wild, unaided by a farmer’s caring hand, the wild varieties learn to become street-smart for survival. They develop resistance to diseases, droughts and other kinds of stresses. So, when breeders want to make their cultivated varieties better, they borrow these extra-powers from the wild cousins.
For example, wild relatives of wheat procured from the Ladakh expedition have shown “resistance to several diseases, tolerance to drought and salinity,” according to Kuldeep Singh, director of NBPGR and one of the researchers on the expedition.
Singh said, “[Some of] these species grow very well along the banks of Pangong lake, which is salty, hence we expect salt tolerance in this species. Likewise, the Ladakh hills do not receive any rains, thus the germplasm [genetic material of plants] that grows in natural mountains without any additional irrigation may also have tolerance to drought.”
The wild side of wheat
The present-day wheat used to make bread and chapati actually originated 10,000 years ago in southwest Asia in an area called the “Fertile Crescent”, the present-day Middle East region extending from the Persian Gulf to Egypt.
Wheat belongs to the genus Triticum, of which there are 10 species. Bread wheat – the most widely grown wheat – was actually produced by crossing a species of wheat with two other species of edible grasses from the genus Aegilops. Historically, humans have been hybridising wheat with its wild relatives for a long time.
The wheat grain made a long journey lasting several thousand years to reach India from the Fertile Crescent. Not much is knon about which wheat varieties first landed here. However, several uncultivated species related to wheat are now found across India. The samples collected by the NBPGR and PAU researchers contain wild relatives mainly of two genera – Elymus and Leymus – which are commonly called “wild rye”.
Of the collected samples, six species of Elymus and one of Leymus were found across a wide altitudinal range. However, at altitudes below 4000 metres, a broader diversity of habitats were occupied by these species.
“Species such as Elymus nutans, E. dahuricus and Leymus secalinus were common weeds in unattended fields, field boundaries, fallows and roadsides”, while E. repens “was found only along riversides and irrigation channels”, write the researchers in their paper. E. nutans and L. secalinus were the most common and widespread of these wheat wild-relatives, found the researchers.
Irrespective of species, specimens collected at higher altitudes (above 3800 metres) contained a purplish-red pigment, especially in the spikes (flower clusters). Although not yet experimentally proven, the scientists believe this could be an adaptation in the Himalayan varieties to withstand UV radiation. As the world continues to warm, traits like the ability to withstand UV radiation will probably become very important for agricultural crops. Previous studies have shown that in a warmer world, exposure to high UV radiation will be one of the stressors affecting the yield of crop plants.
Another threat to wheat production in the face of global warming is its susceptibility to temperature. Current research estimates that for every one degree Celsius rise in temperature, global wheat production may fall by six percent. At present, it is unknown whether the collection of wild wheat-relatives from Ladakh will be able to provide any varieties that are tolerant of heat. However, Singh noted that “groups across the country are evaluating these plants” for their special abilities like heat-resilience and “resistance to several diseases, especially rusts”.
The long road ahead
Conceptually, the idea of transferring desired characteristics from wild plants to cultivated varieties is an ingenious one. But the process of making this transfer is long-drawn and fraught with hurdles. It can take anything from 10 to 15 years to create viable varieties. The biggest challenge lies in “making crosses and producing fertile offspring”, says Benjamin Kilian, Plant Genetic Resources Scientist at The Crop Trust, an organisation working to preserve wild varieties of food crops across the world.
Crosses between these wild plants and cultivated varieties are hard to do because of “species boundaries that exist in nature”, he explains. The wild species in the present collection, though related to wheat, are still “evolutionarily very distant”. In fact, “new biotechnological tools will be required” to transfer the desired traits from these wild relatives to cultivated wheat.
All’s not gloomy, though. Researchers are devising ways to increase the probability of finding the right kind of wild relative – one which is easier to cross and has all the desired traits. They have even seen some success. Scientists from the International Crops Research Institute for the Semi Arid Tropics (ICRISAT) in collaboration with The Crop Trust, have been able to successfully extract disease-resistant traits from wild pigeon peas into a new variety. This new variety will now serve as a donor of disease-resistance for cultivated pigeon pea varieties in India. Creating such donor varieties is an important intermediate step in transferring desired traits from wild to cultivated plants. Therefore, scientists are excited about the future of pigeon pea in India.
As for wheat, the road to creation of a viable variety with traits from its wild cousins is a long one. But scientists are hopeful.
“It may take around 10 years to achieve it. Nevertheless, efforts are on”, said Singh.
Banner image: Cicer microphyllum growing in the wild. Photo from NBPGR.